Big vs. Small - The home theatre Question (Part 1)

I've been thinking about changing my home theatre speaker setup for a little while based on the idea of splitting off a separate stereo kit.
The first real stumbling block I've come up against is 'do you choose a large floor standing setup or a compact satellites/sub combination'?

Obviously the main concern is going to be the sound that is ultimately delivered by the setup. For this Sort Of setup the only source is movies as a separate set of speakers would be pumping out the music.

One key area where the satellites/sub combinations tend to perform is imaging, integration and steering. This is usually because the satellites are identical in their driver configuration if not their entire design. This leads to seamless transition as a specific sound (for example an actor's voice) moves from the centre speaker to one of the front speakers. Obviously this leads to a more realistic movie experience as the tone of the actors voice doesn’t ‘magically’ change as they move around the room. The downfall here is that with their smaller size they are not able to produce the same low level bass information of a floor standing speaker. This information is basically left entirely to the subwoofer and the system relies on entirely on the integration between the subwoofer and satellite to give the impression of the bass information coming from the small enclosure. The first question is here... If you can produce perfect integration between the subwoofer and satellite can produce a comparable sound to that of a similar quality floor standing system?

Not all of us have the space (or the funds) to support a system of 6 B&W Nautilus 801 speakers (or any complete floor standing system) encircling the lounge room. Many manufacturers offer high end satellites but can you ever achieve the fullness of sound compared to a floor stander. If not, is the advantage of imaging and steering worth the sacrifice?